Platen for printing-presses.



PATENTBD APR, 14', 1908.

J. THOMSON.

PLATEN FOR PRINTING PRESSES.

APPLICATION FILED SEPT. 21, 1902.

3 SHEETSSHEET 1.

N0 MODEL.

dlfo'zncua No. 725,637. PATENTBD APR.14, 1903.

J. THOMSON. PLATEN FOR PRINTING PRESSES'.

APPLICATION FILED SEPT. 2'7, 1902.

N0 MODEL. 3 SHEETS-SHEET 2- 3 n can lfoz Ava hwooao W W W attozmeqo No. 725, 37, PATENTED-A-PR. 14', 1903.

J.'THOMSON. v

PLATBN FOR PRINTINGPRESSES.

APPLICATION FILED sum. 27, 1902. no MODEL. 3 SHEETS7SHBET a.

42 LEE-ii.

UNITED STATES JOHN THOMSON, OF BROOKLYN, NEW

PRESS COMPANY, on NEW YORK, N. Y., A

I ATENT OFFICE.

PLAT EN FOR PRlNTlNG-PRESSES.

SPECIFICATION forming part of Letters Patent No. 725,

637, dated April 14, I903.

Application filed September 27, 1902. Serialllo.125,079. mamas.)

To all whmn it may concern:

Be it known that 1, JOHN THOMSON, a citizen of the United States, residing at Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Platens for Printing- Presses, of whichthe following is a specification.

This invention relates to the platens of IO platen printing-presses; and the object thereof is to increase the convenience and durability of operation and to facilitate the construction of the platen and the parts connected thereto.

In the drawings, Figure 1 represents an embodiment of the invention in side elevation. Fig. 2 is a side view of details. Figs. 3 and 4 are detached side and sectional views, respectively, of the ears of the platen; and Fig. 5 is a part side and sectional .view of the platen, showing details of the improved construction.

One feature of invention herein claimed consists in a convenient and effective application of clamps for securing the tympan to the face of the platen O,which platen is shown pivotally mounted on the frame D. This has heretofore been accomplished by means of bails swung over the upper and lower edges 0 of the platen, which are fixedly adjusted to a uniform thickness of tympan and necessarily clamp more tightly at the ends than along the center. These objections are obviated by applying plain strips or bars 31 to the 35 lower and upper edges of the platen and clamped thereto by screws, as 32, at the ends. The bearings for the screws ofthe upper bar are counterbored at 33 to receive springs 34, acting to thrust the bar upwardly; but the 0 thrust upon the lower bar is downward, and the spring is more advantageously applied on the outside. Thus by loosening the screws 32 the bar is caused'to follow, leaving a free space between it and the edge of the platen for the ready insertion, ohange,;stretch, or removal of the tympan. The bars are to be formed or sprung so as to first make contact along the center of the platen, producing a uniform clamping pressure. The screws for the lower bar are elongated, as shown, mou'nted in side pieces 35, so that both the upper and the lower sets may be quickly operated .the walls of the slots, s

to produce free spaces for the ready insertion of the tympan.

Another feature consists of the application to the right and left hand ears 37 of the platen of studs or rollers 38, mounted upon bearings 39, whose centers are eccentric to those of the main bodies 40, secured to the ears with the desired intensity of pressure to resist rotation, as by the bearing-pieces 4.1 and bolts 42. The rollers act in slots 43, formed in the sides of the frame, when the platenis sliding to or from the impression,and their normal functionis to cause the face of the platen to impinge squarely against the form; but in event of an abnormal strain being applied above or below the center, as 4.4, of the platen the eccentric bearings of the rollers will be caused to partially rotate against the friction of the bolts, thus relieving the strain and avoiding fracture of the ears or the walls of the slot. Then, after, by simply loosening the bolts the platen may be reset to parallelism, when the friction may again be applied as before.

I claim- 1. In a platen printing-press, the combina tion with a platen of tympan-clamps secured to the upper and lower edges of the platen by screws and springs arranged to cause the clamps -to leave their seats when the said screws are loosened, substantially as described.

2. .The combination with the frame and bed of a platen-press of a vibrating and sliding platen having studs or rollers mounted on eccentric bearings frictionally secured in the ears thereof and adapted to enter slots in the frame when the impression is being taken, the arrangement and construction being such that an excess of pressure applied above or below the horizontal center of the platen will cause the eccentric bearings to partially revolve and relieve the strain upon ubstantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

' J OHN THOMSON.

Witnesses:-

L. S. FOLGER,

WM. THOMSON. 

